The invention relates to a device for continuously feeding a web of material from a stock roll, comprising a frame, means for rotatably supporting an unwinding stock roll which is present in the device and off which the web of material is coming, means for rotatably supporting a new stock roll placed in the device, means for controlling the peripheral speed of the unwinding roll, means for driving the new roll, and means for adhering the leading end of the web on the new roll to the unwinding web coming off the unwinding roll and severing the unwinding web after the splicing point.
Such a device is known in various embodiments.
In one of the known devices of this type there is a conveyor track for the rolls which runs through the device from front to back. Under this conveyor track are two driving belt units for driving rolls supported by the conveyor track. Each driving belt unit comprises a flat driving belt running round a drive roller and an idler roller. The drive rollers of the two driving belt units are on the bottom side of the device, disposed in the lengthwise direction of the device at some distance from each other. The drive rollers can be driven jointly. Each driving belt unit can be swung about an axis which coincides with the axis of the drive roller thereof, in such a way that the driving belt units can be moved up and down rotating about said axis. When an unwinding roll which is being driven at the periphery by one of the two driving belt units is on the conveyor track, a new roll can be placed on the conveyor track at the beginning of the conveyor track. During the unrolling of the unwinding roll a conveyor belt of the conveyor track moves towards the back, while the periphery of the unwinding roll always remains in contact with the belt of the first driving belt unit, which swings further and further downwards. When the unwinding roll has reached a minimum diameter and a splice has to be made between the leading end of the prepared new roll and the unwinding web, the second driving belt unit is brought into contact with the periphery of the new roll, so that the new roll is run up to speed. The two driving belt units are then driven jointly, so that the two driving belts are running at the same speed. When the unwinding roll and the new roll have reached the same peripheral speed, a splice is made between the leading end of the new roll and the unwinding web, and the unwinding web is severed after the splice point. The first driving belt unit is also moved out of contact with the periphery of the roll which has had the web severed so that this roll is no longer driven. The new roll has now become the unwinding roll which is driven by the second driving belt unit, and the old roll is now a remnant roll. On further movement of the conveyor belt of the conveyor track towards the back, the remnant roll is discharged at the back of the device, while the unwinding roll moves further towards the back. At a certain point in time the drive of the unwinding roller is taken over again by the first driving belt unit, and the second driving belt unit is moved out of contact with the unwinding roll. Thereafter a new roll can be placed again on the conveyor track, and the cycle can be repeated. The web tension of the unwinding web is regulated by means of a dancer during the entire unwinding process.
In another known device of the above-mentioned type, which is described in European Patent Specification No. 0.005.021, there is also a conveyor track running from front to back through the device for conveying the unwinding roll and the new roll through the device. There is, however, only one driving belt unit, which is situated below the conveyor track for the rolls. The driving belt unit here also has a flat driving belt running round a drive roller and an idler roller. The driving belt unit slopes upwards in the direction of movement of the conveyor belt of the conveyor track and can thereby swing about an axis of rotation which coincides with the axis of the drive roller, which is situated on the low side of the driving belt unit, and is itself adjustable in height. When the unwinding roll is being unwound, a new roll can be placed at the beginning of the conveyor belt. During the unwinding of the unwinding roll the conveyor belt of the conveyor track moves towards the back. As the diameter of the unwinding roll becomes smaller, the belt of the driving belt unit resting against the periphery of the unwinding roll moves upwards. At a particular diameter of the unwinding roll, the driving belt comes into contact with the new roll lying on the conveyor track, and said roll thereby runs up to speed and reaches the same peripheral speed as the unwinding roll. At a particular minimum diameter of the unwinding roll a splice is made--in the same way as that described for the abovementioned known device--between the leading end of the web on the new roll and the unwinding web, and the unwinding web is severed. The new roll has now become the unwinding roll. The conveyor belt of the conveyor track now moves further towards the back, so that the remnant roll can be discharged at the rear of the device. The new unwinding roll also moves towards the back, the periphery of this roll always remaining in contact with the driving belt. At a particular position of the new unwinding roll a new roll can be placed again at the beginning of the conveyor track, and the entire cycle can be repeated.
The above-described known devices have the following disadvantages. The remnant roll is deposited at the rear side of the device, so that there is little room for picking up and removing the deposited remnant roll. The remnant roll therefore has to be removed from the side. Another disadvantage is that the new roll is driven at the periphery by a driving belt, which means that a certain part of the leading end of the new roll has to remain free from adhesive. This requires extra care during the preparation of a new roll. It also means that an uninterrupted splice between the leading end of the new roll and the unwinding web is not possible over the width of the web, which is a disadvantage, in view of the impact of air during forward movement of the web.